Telomeric polyfluoroalkyl iodides are commercial products widely used for the preparation of a variety of valuable polyfluorinated compounds. Various processes are known in the art for preparing polyfluoroalkyl iodides based on the telomerization of lower perfluoroolefins (e.g., TFE, tetrafluoroethylene) with fluoroalkyl iodides. A detailed description of the telomerization process is set forth in U.S. Pat. Nos. 3,234,294 and 3,132,185, which are incorporated herein by reference.
The telomerization process typically takes place in the presence of an initiator. Some processes are initiated by peroxy compounds (Ger. Pat. No. DE 2542496; Mar. 31, 1977); some by metals (J. Fluor. Chem. 36(4), 483-489, 1987) or salts of some metals in combination with hydroxyalkylamines (U.S. Pat. No. 4,067,916, Jan. 10, 1978) or initiated by a mixture of IF.sub.5 /SbF.sub.5 (U.S. Pat. No. 3,234,294, Feb. 8, 1966).
It is known in the art that thermal reaction of polyfluoroalkyl iodides R.sub.f I with TFE leads to formation of a mixture of telomeric alkyl iodides R.sub.f (CF.sub.2 CF.sub.2).sub.n I (Telomer A). Bloch (Brit. Pat. No. 1,096,687, 1968; U.S. Pat. No. 3,404,189; 1968; Brit. Pat. No. 1,218,528; 1971) prepared several fluorinated alkyl telomers (for instance, C.sub.6 F.sub.13 I from C.sub.4 F.sub.9 I and TFE) using a high molar ratio of R.sub.f I/TFE, at least greater than 2:1, resulting in low conversion of TFE (10-30%).
A need exists for a telomerization process that does not use added initiators but does result in formation of low molecular weight telomers with a narrow distribution range, a high conversion of reactants but still generates high productivity. The telomers produced herein are useful as intermediates to surfactants and oil repellents.